If little children are reading this page, the first question that comes to mind is: what is population, and what is the definition of the population? So, here's your response. A population is a group of individuals from the same species that live together and interbreed in the same region. Individuals in a population usually rely on the same resources, face comparable environmental limitations, and rely on the availability of other members to survive in the long run . Population demographics, often known as demography, is a branch of science concerned with collecting and evaluating these figures. Any statistical element that influences population growth or decline can be included in demographics, although certain characteristics are particularly important: population size, density, age structure, fecundity (birth rates), mortality (death rates), and the sex ratio. Size, density, fertility, mortality, sex ratio, and age structure are all characteristics that may be measured and ca...